ETWEEN THE LAWS THAT ANY SCHOOL CAN CALL UPON to protect its students from official harassment and the clout that the parents and alumni of a school like Ransom Everglades could muster, it could have been very difficult for us to gather any information on what was now a double disappearance. But the school chose to take the high road and use the crisis as an exercise in community activism. They sat us down in the same office with the cluttered walls while Ms. Stein hustled around alerting teachers and administrators.

I looked around the room and noticed that there were still the same number of chairs. My leaning spot on the wall no longer seemed terribly inviting. But I decided that our significance in the grand scheme of things had gone up several notches when two of the school’s students turned up missing, and, in short, I was now far too important to lean against the wall. And there was, after all, one more perfectly good chair in the room.

I had just settled into Ms. Stein’s chair when my cell phone rang. I glanced at the screen, which told me that the call was from Rita. I answered. “Hello?”

“Dexter, hi, it’s me,” she said.

“That was my first guess,” I told her.

“What? Oh. Anyway, listen,” she said, which didn’t seem necessary, since I was. “The doctor says I’m ready to come home, so can you come get us?”

“You’re what?” I said, completely astonished. After all, Lily Anne had just been born yesterday.

“Ready,” she repeated patiently. “We’re ready to come home.”

“It’s much too soon,” I said.

“The doctor says it’s not,” she said. “Dexter, I’ve done this before.”

“But Lily Anne—she might catch something, or the car seat,” I said, and I realized I was so filled with panic at the thought of Lily Anne leaving the safety of the hospital that I was talking like Rita.

“She’s fine, Dexter, and so am I,” she said. “And we want to come home, so please come pick us up, okay?”

“But Rita,” I said.

“We’ll be waiting,” she said. “Bye.” And she hung up before I could come up with any kind of rational reason for why she shouldn’t leave the hospital yet. I stared at the phone for a moment, and then the thought of Lily Anne actually outside, in a world full of germs and terrorists, galvanized me into action. I slammed the cell phone into its holster and jumped to my feet. “I have to go,” I said to my sister.

“Yeah, I got that,” she said. She threw me her car keys. “Get back here as fast as you can.”

I drove south in pure Miami style, which is to say fast, moving smoothly in and out of traffic as if there were no real lanes. I did not usually drive so flamboyantly; I have always felt that, contrary to the true spirit of our city’s roads, getting there is just as important as maintaining a forceful image along the way. But the moves came naturally to me—I grew up here, after all, and the current situation seemed to call for all the haste and macho firmness I could muster. What was Rita thinking? And more, how had she persuaded the doctors to go along with it? It made no sense: Lily Anne was tiny, fragile, terribly vulnerable, and to send her out into cold hard life so quickly seemed to be complete and callous madness.

I stopped at home just long enough to grab the brand-new infant car seat. I had been practicing for weeks, wanting to be perfect with it when the time came—but the time had come too soon, and I found that my fingers, usually so deft, were icy blocks of clumsiness as I tried to fumble it into place with the seat belt. I couldn’t get it through the slot in the back of the thing at all. I pushed, pulled, and finally cut my finger on the molded plastic and flung the whole thing down as I sucked at the cut.

This was supposed to be safe? How could this protect Lily Anne when it attacked me so aggressively? And even if it worked as it should—and nothing ever did—how could I keep Lily Anne safe in a world like ours? Especially so soon after birth—it was madness to send her home now, one day old. Typical medical arrogance and indifference; doctors think they’re so smart, and all because they passed organic chemistry. But they don’t know everything—they did not see what a father’s heart so clearly told me. It was much too soon to fling Lily Anne out and into the cold cruel world, merely to save a few dollars for the insurance company. This could never end well.

I finally got the car seat in place, and then rushed on to the hospital. But contrary to my perfectly logical fears, when I arrived I did not find Rita standing outside the hospital, dodging bullets while Lily Anne played with used syringes in the trash. Instead, Rita was in a wheelchair in the lobby, a tightly wrapped bundle of baby in her arms. She looked up at me with a loose smile when I rushed in and said, “Dexter, hi, that was very fast.”

“Oh,” I said, trying to register the fact that somehow everything was fine. “Well, actually, I was sort of nearby.”

“You’re not going to drive us home that fast, are you?” she said. And before I could point out that I would never drive fast with Lily Anne in the car and in any case I thought she should stay here a little longer, a cheerful and hairy young man hustled over to us and grabbed at the handles on the back of Rita’s wheelchair.

“Hey, here’s Daddy,” he said. “You folks ready to go?”

“Yes, that’s—Thank you,” Rita said.

The young man blinked and then said, “All righty then,” and he stomped down to release the wheel brake and began to push Rita toward the door. And since at some point even I have to cooperate with the inevitable, I took a deep and resigned breath and followed along behind.

At the car I took Lily Anne from Rita and placed her carefully in the aggressive car seat. But for some reason, all the practicing I had done with Astor’s old Cabbage Patch doll did not quite translate to the real baby; finally Rita had to help me get Lily Anne properly fastened in place. And so it was a completely helpless, all-thumbs Dexter who finally climbed behind the wheel and started the engine. And with many anxious glances in the mirror to make sure that the car seat had not burst into flames, I nosed the car out of the parking lot and onto the street.

“Don’t drive too fast,” Rita told me.

“Yes, dear,” I said.

I drove slowly home—not slowly enough to risk the heavily armed outrage of my fellow citizens, but within spitting distance of the speed limit. Each blast of a horn, every thump of an overcranked car stereo, seemed new and threatening, and when I stopped at red lights I found myself glancing anxiously at the nearby cars to see if any automatic weapons were pointed our way. But somehow, miraculously, we got home safely. Undoing the straps of Lily Anne’s car seat was not nearly as complicated as fastening them, and in no time at all I had her and Rita inside the house and comfortably ensconced on the couch.

I looked at the two of them, and suddenly everything seemed so different now, because for the first time they were here, at home, and just seeing my new baby in this old setting seemed to underline the fact that life was new and wonderful and fragile.

I dawdled shamelessly, soaking it up and reveling in the utter wonder of it all. I touched Lily Anne’s toes, and ran the back of my finger over her cheeks; they were softer than anything I had ever felt before, and somehow I thought I could smell the pink newness of her right through my fingertips. Rita held the baby and slid into a smiling semidoze as I touched and sniffed and looked, until at last I glanced at the clock and saw how much time had passed, and I remembered that I was here in a borrowed car whose owner had been known to verbally behead people for far less.

“You’re sure you’re all right?” I asked Rita.

She opened her eyes and smiled, the ancient smile Leonardo did so well, mother with wonder child. “I’ve done this before, Dexter,” she said. “We’ll be fine.”

“If you’re sure,” I said, with a brand-new sensitivity that I actually felt.

“I’m sure,” she said, and very reluctantly, I left them there.

When I got back to the Ransom Everglades campus with Debs’s car I found that she had been assigned a room in an old wooden building with a view of the bay, as a sort of temporary interrogation room. The Pagoda, as the building was called, perched on a bluff above the athletic field. It was a rickety old wooden building that didn’t look like it could survive a single summer storm, and yet somehow it had stood long enough to become a historical landmark.

Deborah was talking to an exceedingly clean-cut young man when I came in, and she just glanced up at me and nodded without interrupting the boy’s response. I settled into the chair next to her.

For the rest of the day, both students and faculty came into the rickety old building one at a time to tell us what they knew about Samantha Aldovar and Tyler Spanos. The students we saw were all bright, attractive, and polite, and the teachers all seemed to be smart and dedicated, and I began to appreciate the benefits of a private school education. If only I’d had the opportunity to attend a place like this, who knows what I might have become? Perhaps instead of a mere blood-spatter analyst who slunk away at night to kill without conscience, I could have become a doctor, or a physicist, or even a senator who slunk away at night to kill without conscience. It was terribly sad to think of all my wasted potential.

But private education is expensive, and it had been far beyond Harry’s means—and even if he could have afforded it, I doubt that Harry would have gone for it. He had always been wary of elitism, and he believed in all of our public institutions. Even public school—or perhaps especially public school, since it taught a brand of survival skills he knew we would need.

It was clearly a set of skills the two missing girls could have used. By the time Debs and I finished the interviews, around five-thirty, we had learned some very interesting things about both of them, but nothing that suggested they could survive in the wilds of Miami without a credit card and an iPhone.

Samantha Aldovar remained a little bit of a puzzle, even to those who thought they knew her well. The students were aware that she got financial aid, but it seemed to be no big deal to anybody. They all said she was pleasant, quiet, good at math, and had no boyfriend. No one could think of any reason why she would stage her own disappearance. No one could remember ever seeing her hanging around with any kind of disreputable character—except Tyler Spanos.

Tyler was apparently a true wild child, and on the face of things, the friendship between the two girls was extremely unlikely. Where Samantha got a ride to and from school with her mother in a four-year-old Hyundai, Tyler drove her own car—a Porsche. While Samantha was quiet and shy, Tyler seemed to be the original Good Time Charlene, a perpetual loud party just looking for a place to happen. She did not have a boyfriend only because she could not limit herself to one boy at a time.

And yet a close friendship had developed over the last year or so and the two girls were almost always together at lunch, after school, and on weekends. Not only was this puzzling, it was the one thing that bothered Deborah more than any other. She had calmly listened and asked questions, put out a BOLO on Tyler’s Porsche, and (with a shudder) sent her partner, Deke, to talk to the Spanos family, and none of these things had caused so much as a ripple on the face of the Sea of Deborah. But the strange friendship between the two girls had, for some reason, caused her to come up on point like a cocker spaniel sniffing steak.

“It makes no fucking sense,” she said.

“They’re teenagers,” I reminded her. “They’re not supposed to make sense.”

“Wrong,” Deborah said. “Some things always make sense, especially with teenagers. Nerds hang with nerds; jocks and cheerleaders hang with jocks and cheerleaders. That never changes.”

“Perhaps they have some kind of secret mutual interest,” I suggested, glancing casually at my watch, which told me that it was very close to time for me to go home.

“I’d bet on it,” said Debs. “And I’d bet that if we find it, we find out where they are.”

“Nobody else here seems to know what it might be,” I said, even though I was actually trying to construct a graceful exit line.

“What the hell is wrong with you?” Deborah said abruptly.

“Excuse me?”

“You keep squirming around like you have to pee,” she said.

“Oh, um, actually,” I said, “it’s almost time for me to go. I have to pick up Cody and Astor before six.”

My sister stared at me for what seemed like a long time. “I never would have believed it,” she said at last.

“Believed what?”

“That you’d be married, kids, you know. A family man, with all you got going on.”

And by that I knew she meant my darker side, my former role as Dexter the Avenger, the lone blade in the moonlight. She had found out about my alter ego, and had apparently become reconciled with it—and just in time for me to abandon the persona. “Well,” I said, “I don’t suppose I would have believed it either. But …” I shrugged. “Here I am with a family.”

“Yeah,” she said, and she looked away. “And before me.”

I watched her face working to rearrange itself back to her usual mask of perpetual grumpy authority, but it took several moments, and in the interval she looked shockingly vulnerable.

“Do you love her?” she said suddenly, swinging back to face me, and I blinked with surprise. Such a blunt and personal question was very unlike Deborah, which was one reason we got along so well. “Do you love Rita,” she repeated, leaving me no wiggle room whatsoever.

“I … don’t know,” I answered carefully. “I’m, uh, used to her.”

Deborah stared and then shook her head. “Used to her,” she said. “Like she’s an easy chair or something.”

“Not that easy,” I said, trying to inject a little levity into what had suddenly become a very unsettling conversation.

“Do you even feel love at all?” she demanded. “I mean, can you?”

I thought of Lily Anne. “Yes,” I said. “I think so.”

Deborah watched my face for several long seconds, but there was really not much to see, and she finally turned away and looked out through the old wooden window frame at the bay. “Shit,” she said. “Go home. Go get your kids and hang out with your easy-chair wife.”

I had not been human for very long, but even so, I knew something was not quite right in the Land of Deborah and I could not leave her on that note. “Debs,” I said. “What’s wrong?”

I saw her neck muscles tense, but she continued to look away, out over the water. “All this family shit,” she said. “With these two girls and their fucked-up families. And your family with fucked-up you. It’s never what it should be, and it’s never right but everybody gets it except me.” She took a deep breath and shook her head. “And I really want it.” She swung back at me with ferocity. “And no goddamn jokes about the biological clock, all right?”

To be completely honest, which I am when I have to be, I was far too deeply shocked by Deborah’s behavior for any jokes, whether about clocks or anything else. But joke or no, I knew I had to say something, and I cast about for the right thing and could only come up with a question about Kyle Chutsky, her live-in boyfriend of several years. I had seen the approach on a daytime drama a few years back. I liked to study them for clues on how to act in ordinary situations, and it looked like that was going to pay off here. “Is everything okay with Kyle?” I said.

She snorted, but her face softened. “Fucking Chutsky. Thinks he’s too old and beat-up and useless for a nice young thing like me. Keeps saying I can do better. And when I say maybe I don’t want to do better, he just shakes his head and looks sorrowful.”

It was all very interesting, a truly riveting look into the life of someone who had been a human being much longer than I had, but I was all out of ideas for constructive commentary, and I felt very much the pressure of the clock—the one on my wrist, not the biological one. So, floundering about for something to say that would be properly comforting and yet hint at my need for immediate departure, all I could come up with was, “Well, I’m sure he means well.”

Deborah stared at me long enough to make me wonder if I had really said the right thing. Then she sighed heavily and turned to face out the window again. “Yeah,” she said. “I’m sure he means well, too.” And she looked out at the bay and didn’t say anything but, worse than any words she could have uttered, she actually sighed.

This was a side of my sister I had not seen before, and it was not a side I wanted to see a great deal more of. I was used to Deborah being full of sound and fury, signifying arm punches. To see her soft and vulnerable and roiling with self-pity was unsettling in the extreme. Even though I knew I should say something comforting, I had no idea where to begin, and so I stood there awkwardly, until finally the need to leave was stronger than my sense of obligation.

“I’m sorry, Debs,” I said, and oddly enough, I was. “I have to get the kids now.”

“Yeah,” she said without turning around. “Go get your kids.”

“Um,” I said, “I need a ride, back to my car.”

She turned slowly away from the window and looked over at the building’s door, where Ms. Stein was hovering. Then she nodded and stood up. “All right,” she said. “We’re done here.” She walked past me, paused only to thank Ms. Stein with flat politeness, and led the way back to her car in silence.

The silence lasted almost all the way to my car and it was not very comfortable. I felt like I should say something, lift the mood a bit, but my first two attempts fell so flat that I stopped trying. Debs pulled into the parking lot at work and stopped beside my car, staring straight ahead through the windshield with the same look of unhappy introspection she’d been wearing for the whole trip. I watched her for a moment, but she didn’t look back.

“All right,” I said at last. “See you tomorrow.”

“What’s it like?” she said, and I paused with the door half-open.

“What’s what like?” I said.

“When you held your baby for the first time,” she said.

I didn’t have to think very hard to answer that. “Amazing,” I said. “Absolutely wonderful. It’s not like anything else in the world.”

She looked at me, and I couldn’t tell whether she was going to hug me or hit me, but she didn’t do either, and finally she just shook her head, slowly. “Go get your kids,” she said. I waited for a second, to see if she would say anything else, but she didn’t.

I got out of the car and as she drove slowly away I stood and watched, trying to fathom what was going on with my sister. But it was clearly something far too complicated for a newly minted human, so I shrugged it off, got into my car, and went to get Cody and Astor.